Image: tongue of a rat stained with hematoxylin and eosin.
Epithelium: it is a layer of keratinized squamous stratified epithelium. Many filiform papillae are observed.
Filifirm papilla: they are specializations of the epithelium and underlying connective tissue. Filiform papillae are very abundant in the tongue. They make a harsh surface that helps to move the food in the oral cavity.
Mitotic cell: in the basal layer of the epithelium, there is an intense cellular proliferation for renewing the epithelium.
Mucous gland: these secretory cells show a light cytoplasm because their content is not stained with hematoxylin and eosin. Their nuclei are flattened and found at the basal part of the cell.
Serous gland: these secretory cells show a darker cytoplasm due to the high content of enzymes, mainly amylases. Their nuclei are more rounded and are found in a central position when compared with mucous cells.
Excretory duct: it conducts the substances released by secretory cells to the outer surface of the tongue, and therefore to the oral cavity.
Skeletal muscle: the tongue mostly consists of skeletal striated muscle cells. It is a voluntary muscle. The skeletal muscles cells are arranged in all directions and can produce very complex movements of the tongue.